Claude Haiku 4.5 vs Mercury 2
Claude Haiku 4.5 leads Mercury 2 on the Artificial Analysis Intelligence Index, 16.9 to 10.8, and Mercury 2 costs 6.7x less per output token ($0.75 vs $5.00 per million). Updated October 22, 2026; 34 benchmarks have a result for both.
Claude Haiku 4.5 or Mercury 2: which to pick
Only Claude Haiku 4.5 has a coding score, 35.6 on the Vibe Coding Index; Mercury 2 has none, so the two cannot be ranked on coding.
Pick Mercury 2 for output tokens 6.7x cheaper ($0.75 vs $5.00 per million).
- Shared results
- 34
- Claude Haiku 4.5 only
- 64
- Mercury 2 only
- 8
- Like-for-like categories
- 7 of 9
Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, six public coding benchmarks
No call
Only Claude Haiku 4.5 has a coding score, so no call is made.
One side not measured
Intelligence
AA Intelligence Index
Claude Haiku 4.5
Claude Haiku 4.5 leads, 16.9 against 10.8.
Same board, both measured
Agentic work
AA Agentic Index
Claude Haiku 4.5
Claude Haiku 4.5 leads, 8.0 against 1.6.
Same board, both measured
Reasoning
GPQA Diamond
No call
Only Claude Haiku 4.5 has a GPQA Diamond result, 72.2%.
Directional only
Math
AIME
No call
Only Claude Haiku 4.5 has a AIME result, 82.7%.
Directional only
Knowledge
MMLU Pro
No call
Only Claude Haiku 4.5 has a MMLU Pro result, 78.7%.
Directional only
Web design
Design Arena: websites
Claude Haiku 4.5
Claude Haiku 4.5 leads, 1122 against 1035.
Same board, both measured
Long documents
Listed context window
Claude Haiku 4.5
Claude Haiku 4.5 takes 200K tokens against 128K.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Mercury 2
Claude Haiku 4.5 $0.0035, Mercury 2 $0.0006 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Claude Haiku 4.5 has the number, $0.56.
Directional only
At a glance
- Coding index
- Claude Haiku 4.5 35.6 from 4 benchmarks, Mercury 2 not benchmarked.
- Widest category
- Coding, 14.4 points apart on average over 7 shared benchmarks.
- Widest single gap
- LMArena WebDev: React: Claude Haiku 4.5 1326 against Mercury 2 1160, 27.8 points apart on a 0 to 100 scale.
- Output price
- Claude Haiku 4.5 $5.00 against Mercury 2 $0.75 per million output tokens, 6.7x apart.
- Context window
- Claude Haiku 4.5 takes 200K tokens, Mercury 2 128K.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Claude Haiku 4.5 | Bars | Mercury 2 | Ties |
|---|---|---|---|---|
| Coding | 7 | 0 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 1 | 0 | ||
| Reasoning | 3 | 0 | ||
| Knowledge | 3 | 0 | ||
| Web design | 8 | 0 | ||
| General | 11 | 0 | ||
| All shared boards | 34 | 0 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index70
| Benchmark | Claude Haiku 4.5 | Mercury 2 | Leader |
|---|---|---|---|
| SWE-bench Verified | 66.6% | Not measured | Only Claude Haiku 4.5 measured |
| SWE-bench Multilingual | 64.7% | Not measured | Only Claude Haiku 4.5 measured |
| LiveBench coding | 48.1% | Not measured | Only Claude Haiku 4.5 measured |
| LMArena WebDev | 1330 | 1171 | Claude Haiku 4.5 |
| AA Coding Index | 43.9 | 31.1 | Claude Haiku 4.5 |
| LiveCodeBench (Vals AI) | 41.2% | Not measured | Only Claude Haiku 4.5 measured |
| SWE-bench Verified (Vals AI) | 66.6% | Not measured | Only Claude Haiku 4.5 measured |
| Vibe Code Bench (Vals AI) | 11.4% | Not measured | Only Claude Haiku 4.5 measured |
| Code migration (Vals AI) | 7.5% | Not measured | Only Claude Haiku 4.5 measured |
| ProgramBench (Vals AI) | 0.0% | Not measured | Only Claude Haiku 4.5 measured |
| Terminal-Bench 2.1 (Vals AI) | 43.8% | Not measured | Only Claude Haiku 4.5 measured |
| SciCode | Not measured | 37.7% | Only Mercury 2 measured |
| Terminal-Bench Hard (Artificial Analysis run) | Not measured | 26.5% | Only Mercury 2 measured |
| Terminal-Bench | 35.5% | Not measured | Only Claude Haiku 4.5 measured |
| WeirdML | 45.4% | 43.2% | Claude Haiku 4.5 |
| ALE-Bench | Not measured | 785.6 | Only Mercury 2 measured |
| LMArena Text: coding | 1454 | 1390 | Claude Haiku 4.5 |
| LMArena Text: software and IT | 1439 | 1385 | Claude Haiku 4.5 |
| LMArena WebDev: React | 1326 | 1160 | Claude Haiku 4.5 |
| LMArena WebDev: HTML | 1318 | 1199 | Claude Haiku 4.5 |
| Neither model has a result on the other 23 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Haiku 4.5 | Mercury 2 | Leader |
|---|---|---|---|
| AA Intelligence Index | 16.9 | 10.8 | Claude Haiku 4.5 |
| Epoch Capabilities Index | 142.2 | Not measured | Only Claude Haiku 4.5 measured |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Haiku 4.5 | Mercury 2 | Leader |
|---|---|---|---|
| AA Agentic Index | 8.0 | 1.6 | Claude Haiku 4.5 |
| LiveBench research | 42.2% | Not measured | Only Claude Haiku 4.5 measured |
| LiveBench browser | 40.0% | Not measured | Only Claude Haiku 4.5 measured |
| LiveBench long agentic | 11.1% | Not measured | Only Claude Haiku 4.5 measured |
| Finance Agent (Vals AI) | 31.0% | Not measured | Only Claude Haiku 4.5 measured |
| Tax Agent Bench (Vals AI) | 5.9% | Not measured | Only Claude Haiku 4.5 measured |
| Legal Research Bench (Vals AI) | 10.6% | Not measured | Only Claude Haiku 4.5 measured |
| Excel Modeling Benchmark (Vals AI) | 22.7% | Not measured | Only Claude Haiku 4.5 measured |
| τ²-Bench Telecom | Not measured | 70.8% | Only Mercury 2 measured |
| BALROG | 31.2% | Not measured | Only Claude Haiku 4.5 measured |
| DeepResearch Bench | 45.5% | Not measured | Only Claude Haiku 4.5 measured |
| Vending-Bench 2 | $459 | Not measured | Only Claude Haiku 4.5 measured |
| Berkeley Function Calling Leaderboard (BFCL) | 68.7% | Not measured | Only Claude Haiku 4.5 measured |
| MCP Atlas | 40.2% | Not measured | Only Claude Haiku 4.5 measured |
| Neither model has a result on the other 28 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Claude Haiku 4.5 | Mercury 2 | Leader |
|---|---|---|---|
| GPQA Diamond | 72.2% | Not measured | Only Claude Haiku 4.5 measured |
| LiveBench reasoning | 61.7% | Not measured | Only Claude Haiku 4.5 measured |
| MMMU Pro (Vals AI) | 46.1% | Not measured | Only Claude Haiku 4.5 measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 77.0% | Only Mercury 2 measured |
| Humanity's Last Exam (Artificial Analysis run) | Not measured | 17.1% | Only Mercury 2 measured |
| GPQA Diamond (Epoch AI run) | 71.2% | Not measured | Only Claude Haiku 4.5 measured |
| ARC-AGI | 47.7% | Not measured | Only Claude Haiku 4.5 measured |
| ARC-AGI-2 | 4.0% | Not measured | Only Claude Haiku 4.5 measured |
| Chess puzzles | 8.0% | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: hard prompts | 1421 | 1362 | Claude Haiku 4.5 |
| LMArena Text: expert | 1443 | 1358 | Claude Haiku 4.5 |
| LMArena Text: hard prompts in English | 1435 | 1374 | Claude Haiku 4.5 |
| Neither model has a result on the other 11 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
| Benchmark | Claude Haiku 4.5 | Mercury 2 | Leader |
|---|---|---|---|
| AIME | 82.7% | Not measured | Only Claude Haiku 4.5 measured |
| MGSM (Vals AI) | 92.2% | Not measured | Only Claude Haiku 4.5 measured |
| OTIS Mock AIME | 66.7% | Not measured | Only Claude Haiku 4.5 measured |
| MATH level 5 | 96.4% | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: math | 1398 | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: mathematical work | 1430 | Not measured | Only Claude Haiku 4.5 measured |
| Neither model has a result on the other 8 boards here | |||
KnowledgeLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Claude Haiku 4.5 | Mercury 2 | Leader |
|---|---|---|---|
| MMLU Pro | 78.7% | Not measured | Only Claude Haiku 4.5 measured |
| LegalBench (Vals AI) | 81.2% | Not measured | Only Claude Haiku 4.5 measured |
| CaseLaw (Vals AI) | 56.5% | Not measured | Only Claude Haiku 4.5 measured |
| CorpFin (Vals AI) | 60.6% | Not measured | Only Claude Haiku 4.5 measured |
| TaxEval (Vals AI) | 67.5% | Not measured | Only Claude Haiku 4.5 measured |
| MortgageTax (Vals AI) | 62.2% | Not measured | Only Claude Haiku 4.5 measured |
| MedQA (Vals AI) | 79.6% | Not measured | Only Claude Haiku 4.5 measured |
| MedCode (Vals AI) | 32.7% | Not measured | Only Claude Haiku 4.5 measured |
| SimpleQA Verified | 13.2% | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: science | 1406 | 1343 | Claude Haiku 4.5 |
| LMArena Text: medicine and healthcare | 1394 | 1363 | Claude Haiku 4.5 |
| LMArena Text: legal and government | 1400 | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: business and finance | 1400 | 1349 | Claude Haiku 4.5 |
| Neither model has a result on the other 7 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index80
| Benchmark | Claude Haiku 4.5 | Mercury 2 | Leader |
|---|---|---|---|
| Design Arena: websites | 1122 | 1035 | Claude Haiku 4.5 |
| Design Arena: UI components | 1097 | 996 | Claude Haiku 4.5 |
| Design Arena: game dev | 1096 | 983 | Claude Haiku 4.5 |
| Design Arena: data viz | 1124 | 1010 | Claude Haiku 4.5 |
| Design Arena: 3D | 1071 | 982 | Claude Haiku 4.5 |
| Design Arena: all code categories | 1114 | 1021 | Claude Haiku 4.5 |
| Design Arena: SVG | 1025 | 997 | Claude Haiku 4.5 |
| Design Arena: ASCII art | 1140 | 988 | Claude Haiku 4.5 |
| LiveBench design | 59.9% | Not measured | Only Claude Haiku 4.5 measured |
GeneralLike-for-likePublic boards, shown as published, kept out of the index110
| Benchmark | Claude Haiku 4.5 | Mercury 2 | Leader |
|---|---|---|---|
| LiveBench data analysis | 59.3% | Not measured | Only Claude Haiku 4.5 measured |
| Public Benefits Bench (Vals AI) | 54.3% | Not measured | Only Claude Haiku 4.5 measured |
| SAGE (Vals AI) | 31.8% | Not measured | Only Claude Haiku 4.5 measured |
| MedScribe (Vals AI) | 85.2% | Not measured | Only Claude Haiku 4.5 measured |
| Vals Multimodal Index | 42.9% | Not measured | Only Claude Haiku 4.5 measured |
| IFBench | Not measured | 69.8% | Only Mercury 2 measured |
| Long context reasoning (AA-LCR) | Not measured | 43.7% | Only Mercury 2 measured |
| DTBench | 73.6% | Not measured | Only Claude Haiku 4.5 measured |
| LMCA | 30.9% | Not measured | Only Claude Haiku 4.5 measured |
| ExploitBench | 13.7% | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text | 1397 | 1354 | Claude Haiku 4.5 |
| LMArena Text: instruction following | 1414 | 1328 | Claude Haiku 4.5 |
| LMArena Text: creative writing | 1371 | 1286 | Claude Haiku 4.5 |
| LMArena Text: English | 1414 | 1378 | Claude Haiku 4.5 |
| LMArena Text: non-English | 1377 | 1330 | Claude Haiku 4.5 |
| LMArena Text: Chinese | 1418 | 1414 | Claude Haiku 4.5 |
| LMArena Text: German | 1374 | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: Japanese | 1338 | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: Korean | 1346 | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: French | 1411 | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: Spanish | 1421 | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: Russian | 1381 | 1304 | Claude Haiku 4.5 |
| LMArena Text: Polish | 1343 | Not measured | Only Claude Haiku 4.5 measured |
| LMArena Text: multi-turn | 1409 | 1357 | Claude Haiku 4.5 |
| LMArena Text: longer queries | 1427 | 1329 | Claude Haiku 4.5 |
| LMArena Text: writing and language | 1386 | 1300 | Claude Haiku 4.5 |
| LMArena Text: entertainment and media | 1369 | 1314 | Claude Haiku 4.5 |
| LMArena Document | 1420 | Not measured | Only Claude Haiku 4.5 measured |
| MultiChallenge | 50.5% | Not measured | Only Claude Haiku 4.5 measured |
| EQ-Bench 4 | 1064 | Not measured | Only Claude Haiku 4.5 measured |
| Neither model has a result on the other 18 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Haiku 4.5 | Mercury 2 | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Mercury 2 costs less
Repository review
50K input + 3K output tokens
Mercury 2 costs less
Agent loop
200K input + 10K output tokens
Mercury 2 costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Anthropic Claude Haiku 4.5 | Inception Mercury 2 |
|---|---|---|
| Maker | Anthropic | Inception |
| Weights | No public weights listed | No public weights listed |
| Released | October 15, 2025 | March 4, 2026 |
| Context window | 200K | 128K |
| Input $/Mtok | $1.00 | $0.25 |
| Output $/Mtok | $5.00 | $0.75 |
| Coding index | 35.6 | Not benchmarked |
| Independent measurements behind it | 4 | 1 |
| Cost per solved task | $0.56 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Haiku 4.5 better than Mercury 2 for coding?
Only Claude Haiku 4.5 has a coding score, 35.6 on the Vibe Coding Index; Mercury 2 has none, so the two cannot be ranked on coding. Pick Mercury 2 for output tokens 6.7x cheaper ($0.75 vs $5.00 per million).
Which is cheaper, Claude Haiku 4.5 or Mercury 2?
Claude Haiku 4.5 costs $1.00 per million input tokens and $5.00 per million output tokens; Mercury 2 costs $0.25 and $0.75. Cost per solved task is known for Claude Haiku 4.5 only.
Which has the bigger context window, Claude Haiku 4.5 or Mercury 2?
Claude Haiku 4.5, with 200K tokens against 128K.
How many benchmarks is the Claude Haiku 4.5 vs Mercury 2 comparison based on?
34 benchmarks have a result for both models as of October 22, 2026. Claude Haiku 4.5's coding index rests on 4 independent benchmarks and Mercury 2's on 1. Where only one model has a result, the page says so instead of naming a winner.